Electrical contact element



July 15, 1924. 1,501,330

B. J. GUDGE ET Al.

ELECTRI CAL ELEMENT Filed May 12 1919 WITNESSES:

mvan o as Benjamin U e WWW au/ a Guesf y ATTORNEY Patented July 15, 1924.

ELECTRICAL coN'rAc'r'ELEMEN'f.

Application filed May 12, 1919. Serial No. 2 913,428.

To all whom it may concern:

it known that we, BENJAMIN J. Gonen,

a citizen of the United States, and a resident of Wilkinsburg,

in the county of Alleghely 5 and State of Pennsylvania, and PAUL.

Gunsr, a citizen of the United States, and a resident of. Wilkinsburg, in the county of Allegheny. and State invented a new and Electrical Contact Elements,

of Pennsylvania, have useful Im rovement in of. which the following is a specification. A

Our invention'relates to electrical conduc tors or contact larly bers for employment in switches, the like, and it elements and more particuelements or bridging memrelays and for its primary object,

to contact the provision of a carboniferous composition particularly adapted, for employment for Heretofore, members have vided carbon,

because of its strength, such purposes.

carbon conductors or contact been molded from finely dior equivalent material, to-

gether with some binder, usually of an organic nature,

body

to drive oil the such as a pitch. The molded has then been baked in powdered coke volatile portion of the pitch and to transform the remainder into a binding carbon. For instance, contacts are in the form of when the desired disks for relays,

it has been common to mold a cylindrical body of carbon with an organic binder, as

. above described. This body would then be sawed, or otherwise cut, transversely to pro-' vide desired thickness which a plurality of disk-shaped sections of might then be formed with central openings to receive insulating sleeves or bushings so* that they It has been -found, however, that considerable difliculty insulating the disks from the was met with in. properly ing shipment of the sequent use.

relays and in their sub- W e have now found that a carbon contact member of far greater mechanical stren th may be provided by employing a suita le binder which remains a permanent portion of the molded carboniferous body and that a bin ler comprising a phenolic condensation ends of relay plunger and product is purpose.

We have further ascertained that, by molding the carbon material, together with a suitable backing material, comprising an insulating composition of relatively great mechanical strength, the contact or bridging members may be still further reinforced and strengthened. Furthermore, when these members are-in the form of disks for attachment to the plungers of relays, we have found that it is advisable to form them with central openings and to mold therein hubs of the insulating material at the same time that the backing of such material is provided. 3 In view of these facts, one object of our invention resides in providing a contact member for relays essentially comprising an annular body of carboniferous conducting material, and a binder, such as a phenolic condensation product, provided with a hub portion and a backing of an insulating composition which shall serve not only to reinforce the contact memberproper but also as a means for insulating it from a relay particularly adapted for the plunger, or equivalent element, to which it binder will not materially increase the resistance of the contact member.

Nevertheless, with currents of high amperage, this increase in resistance ofthe contact member may .be serious, and, for this reason, another object of our invention consists in providing means for greatly reduc' ing the resistance which contact members of this character would otherwise offer to the passage of current.

With these and other objects in view, our invention Will be more fully described, illustrated in the drawings, in the several views of which corresponding numerals ind1cate like parts, and then particularlypointed outv in the claims.

Fig; 1 is a view, partially in elevation and partially in section, of a relay equipped with a contact or bridging member confrom finely divided carbon and a binder which is subsequently carbonized, are unsatisfactory because of their low mechanical strength, much stronger elements of this character may be provided by the employment of a. binder whichremalns a perma- 'nent part of the composition, such as a phenolic condensation product, For example, such bodies or articles may be readily provided by thoroughly mixing or mingling nely divided carbon with a phenolic condensation product, in suitable proportions. Preferably, as little of the phenolic condensation product should be employed as will give the resultant body the requisite mechanical strength. The proportions of the carbon to the phenolic condensation product may, however, be considerably varied, 'such proportions being dependent upon the mechanical strength required and upon whether or not it is essential that the body shall offer as little resistance to the passageof electrical current as possible. We have ascertained that bodies comprising 90% carbon and 10% of the binder are very satisfactory. The mixed binder and carbon may be brought to any desired shape by subjecting the compositionto heat and pressure in a suitable mold to shape the body and convert the binder to its final, hard and substantially insoluble and infusible condition.

If unusual strength is desired in contact or bridging members of this character, they may be reinforced by a body'of moldable composition which shall preferably be one having insulating properties. Such body may be molded and cured at the same time as the conducting element to provide, with it, a single, unitary article in which the conducting material and reinforcing material are relatively localized in any desired manner. For instance, the insulating material may form a backing for one face of the conducting element or it may, in addition, provide means for securing the article, as a whole, to any desired relay or switch member in such manner as to insulate the conducting element therefrom.

Where it is requisite that the conducting element, or contact, shall offer a minimum resistance to the passage of an electric current, suitable means-may be provided for reducing the resistance which the body of molded carbon and a phenolic condensation product, as a binder, would offer. For instance, metallic conductor elements may be imbedded within the carbon composition, in

any suitable manner, as by the employment of metal gauze or,'in case the conducting ,portion of the member is provided with a reinforcing backing of non-conducting material, copper gauze or equivalent conducting means may be molded into the body between the conducting and" the backing mateinto {operative engagement with spaced con- I tacts 4;

lhe construction of the contact or brid ing member 3, which is illustrative of on y one of numerous possible embodiments of our invention, may bestbe understood by reference to Figs. 2 and 3 of the drawing. As here shown, the conductor member comprises an annular, conducting portion 5, which may be of any width and thickness,

provided with a hub 6 and backing 7 of nonconducting material, the hub'being formed.

with an opening 8 for convenient attach ment to the plunger of the relay. Suitable conducting and reinforcing elements may be molded into the conducting portion 5 of the member or between such portion and the backing portion 7 thereof to decrease its resistanbe and, as best shown in Figs. and 3, the conducting elements may comprise an annular sheet of metallic gauze 9.

When practising our invention, to manufacture an article of the kind shown in the properties to provide the hub portion an backing of the contact member. A composition suitable for this purpose may comprise a mixture of wood flour or asbestos and aphenolic condensation product in suitable proportions, as, for example, substantially 60% of wood flour and 40% of a phenolic condensation product.

The materials thus assembled in the mold may th n be subjected to the pressure to properl form the hub and backing portions t ereof and to heat to harden the ers may be employed for the carbon portion, such as sugar. As such a carbon composition must be baked at a relatively high temperature, asbestos should be substituted for *wood flour as the filler for the backin %t will, of course, be understood that, if metallic gauze or its equivalent is to be incorporated in the body, to reduce the resistance of the conducting material,-it will either be molded in the conducting portion of the body or between such portion and the backing portion thereof. The gauze or its equivalent, however, is only required under certain circumstances, such as where circuits of high amperage will be encountered.

, By practising our foregoing invention, We have found that it is possible to provide electrical conductors or contact members, of carbon and a binder, which are much stronger mechanically than those previously known to us. We have further found that we may reinforce such members in a simple and inexpensive manner by providing them with backing and attaching portions of moldable insulating material of such character that both the conducting portions and insulating portions of the body may be molded and joined together at the same time and by the same molding or curing treatment.

Furthermore, if desirable, the resistance of the conducting portion of the member may be materially decreased by molding into it, or between it and the reinforcing portion of the member, a metallic element or elements in the form of gauze or the like.

While .we have illustrated our invention as embodied in a relay, it will be appreciated that it is adaptable to a wide range of purposes and to numerous articles and, for that reason, no limitations are to be imposed upon our invention, other than those indicated in the claims in which it is our intention to cover it as. broadly as maybe permitted by .the state of the art.

We claim as our invention:

. 1. An electrical conducting element comprising a molded body formed partly of carbon and a binder and partly of insulating material, the materials being localized in definite portions of the body.

2. An elect ical conducting element comprising a con ucting portion of carbon and a phenolic condensation product as a binder and a reinforcing backing portion molded 'thereto and comprising an insulating composition.

3. An electrical conducting element comprising a conducting portion and an insulating portion, each having a heat-hardened binder, said portions being intimately joined. I

4.. An electrical conducting element comprising a conducting portion of carbon and a phenolic condensation product and a reinforcing, backing portion of a comminuted filler and a phenolic condensation product as a binder, the binder of both portions being hardened by the application of heat and pressure. K

5. A contact member for relays comprising a disk of finely divided carbon associated with a heat-hardened phenolic condensation product and a backing and hub portion of insulating material.

6. A contact member for relays comprising a disk of finely divided carbon associated with a heat-hardened phenolic condensation product and a backing and hubportion of a comminuted filler and a hardened phenolic condensation product.

7. Acontact for relays comprising a diskshaped body, one face of which is formed of finely divided carbon and a hardened phenolic condensation product as a binder and'the other face of which is formed of a comminuted filler and a similar hardened binder.

8. A contact for relays comprising a diskshaped body, one face of which is formed of finely divided carbon. and a hardened phenolic condensation product as a binder and the other face and hub portion of which are formed of a comminuted filler and a similar hardened binder, and metallic gauze molded between the materials.

In testimony whereof, we have hereunto subscribed our names this 30th day of April,

BENJ. J. GUDGE. PAULG. GUEST. 

